SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0be6071ef6aab2cdca9158650426dde899be4d20f19aca90f93c25a5cdd03591' 
  AND token = 'Mm0Zvh7IDJZ6zE754Hv5jDMPQ8+gi8YKL1n3woZlXrk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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