SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51b6d08c7dc099d1970a04d653488d3345466540e3e29e3f0be21a278c911f6a' 
  AND token = 'zGDlfGxrvBG7ySSzsWWJWKaLrkJLcbgKF7qT+UDxw8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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