SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3a266825a3836080687a0ac389e6cdb228abad7a73bc73df6086cecfa74a4d5' 
  AND token = 'M0t9IjNt1+DQ1uDkgMohp+fZbnh3utywUUW94CMqHdI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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