SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1ab8ff3756c2dce0998e3d14c7078b0b546928367484747077db1cf69bda77e' 
  AND token = 'xJNB0EnLM6LtNwxVMpFuMgAM0ART5k0VXqcwHEFG86w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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