SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb62da664657021602438ac0de6b0aa432413a1ac09ae5e697025913ae4cb716' 
  AND token = 'l6IlGZQ9RCttV7aLvfUcR2vAAfxw3AhlIa/JlHX1EV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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