SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8551dab08c3dd56f594ab0734c4ec4b148d334218e4661ef44382d76e0d5774' 
  AND token = 'r2RLmgcz+VulTnHAhiJlZ7+EJgf0gNTIPQnVelVV6xc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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