SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b37fc696f901d5b171a042140989597127846e5238626dec2f935de839c5da15' 
  AND token = 'Zmef8+3x8s1ybeflZ5+tZdJapypvD8Fg5leYm2tmksc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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