SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '938b39c456951903ab401f8dfef7dce516739ac26ca2ddf88ed4b5ffd59261c0' 
  AND token = 'QyhRKOZr1lsQQD0trsQbti5dwqqG0DO1+Z9/NtmR9ZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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