SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '756dd322ccdc103445bc92fd2ae960652ee365a7956b5b4a1396207ea6abb9a3' 
  AND token = 'wVs5xO5kYDFppTKxNLu/xD1ggciiBAQLugPWjGfvimI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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