SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b04d577bfb8b04c32009461df25c92f567624cb9628d9836e12d8bb07e97df74' 
  AND token = 'S7cqxJPnGXRLGkV17jPIIQOmqWzXnK7n56acYosH+tE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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