SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b868834d9432ffe453cf4dfddbbf7a996a289302fed888553a93df8dfe745506' 
  AND token = '0BP147akFfmbo+3rSLbXm/+Os3BcKWAS1CkMy2ryh98=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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