SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7fd4b329577cb78d98869bf80034226148f0c80ce9a04cde66d2c1ca11e58b2a' 
  AND token = '57eM7+3FWUp9He+a7TsWoeBVSHp9lgjxcNEcOrEqVYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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