SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c9c8399242611bead1846e70c64d6f515d51a18368ba69905a2ef20d71c454e' 
  AND token = '34AwI5bjb/P4oZlUb9IZNCYpcHZb5if/R9DGdvjusqw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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