SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '753ff9db8670bed504e5dd825d1ccbbd20bfa1d1cb976cc02e09fd06f2bc651c' 
  AND token = 'p/rvE20Q6Rs3c9ksPcZ/sdBY4heW8kTFlFFIfhN5UPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00071

JSON explain

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