SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e62a5d46751822fbadf738d53a0addefb7b29743613c728308a0a2dbaac66430' 
  AND token = 'kvC7+qYCNmzIsBGjR9QOhVkX5IkKt+I7R5XuFqZcgCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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