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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa31fae651abd0271e1e658776d57b2e075790088e5e4ae186e8acbfb4808f36' 
  AND token = 'Y/NO6Qv6sm+tMxLi15j/UuLVVmyOvsHY4xwoQK8BLpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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