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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2171f08ab23a42b2993010fb467e6d5d3f17eb3a5ad8de14cdd480e26c565f76' 
  AND token = 'kJkB1+AxJ1XrBT0Btk3oyS9hs3TYET4OIWcnFAVV9Ss=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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