SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4678ed531468e8eeb823a3ce3ba5eae196e04d447eec0399ddcdf10223a02c11' 
  AND token = '4hYk6INgUUHHDHPMvQ3IiGMANqF+ruJIL2JqTIC3zr4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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