SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2553eee8be8c49fa8bde17d5c0051bc52bf751d6cb9aca55d38b5a0b4e545b2d' 
  AND token = 'mdvjQhFixAflgouiXOMyZjMTJub6Oxqpi9gQXijhsJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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