SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c73b03efebf61bcd79ace749b132ad1547a31415f14ecad58462d54b466787e' 
  AND token = 'MdUMW0EzddVwJmLdwUy990EnDyCmex3dVlcNr/vACHM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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