SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd003f402efe00dff73db1330b331f27f71d55bd35d007464099afa78ed146834' 
  AND token = 'uPGTpFQ2gM39Mpt8DYZx1AdkDKpvzQvPntZJJRuSRrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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