SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4d5d06a98c41ecda663b1c36425dbd4c54c426c9ff1ba152b5ba39e47baf38d' 
  AND token = 'NLWoJ8YrhvQvQP+jJLr+S+ZQkVpTQ3KK3G5oC1BJ1z4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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