SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b76c30d3b33cc1a868751dd2b52d2692b0ad27b51df33342953534101679749' 
  AND token = 'sGvpTkbB7pSpRTnj+Qe5ngK3Bev6nzJV1alrhaZdGlo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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