SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '929e4ca54c20c99d0aa262f4068c6faf96dcffeaec2908f531da3f2a2322d4c4' 
  AND token = 'wA0esQrcPtm6umJH+bLxVGYejHN3VzPojz/s0GiGZhQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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