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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2dddfa1bb2c2906ee796da434e04b7a5296a9a8f5384e531c30b00e7b262b57f' 
  AND token = 'M6qoWnhPyBB0OF+yyve7K7Qa0gafDqLQ1RidDzwQuC4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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