SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75760975ace1255e89f4e8972365b726e2df1343e9aa24394d423aeb12c1636b' 
  AND token = 'Ppb7BHTprKrulefB8alUyVE8DqxTdvDMfSph/Ooc3b0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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