SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c85b812f19a8d0aefd42305c0d1d7466cf6401fbf21402f0649d279abd426004' 
  AND token = 'V42wfXbkzrzHKsV+gfmnrRjr0OrFaITh4lVKT4+Rf/8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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