SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd584473f66c2b75fae6922e12603aacbcec0a6b2e57e21c757d78700866c5f6c' 
  AND token = 'h18z4g+1hXnKhQAxKxPMDcuQYkjsEL34TsZZQB/YJ/Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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