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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8a4554b3e616787aaeb7a8434a5d8cbfa1980fb6eae4eee4b8a31ee39b8c268' 
  AND token = '6OXdyE/oSZtOT/KueemuW/w/OFPb0gDH1KVqvCMqvbI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}