SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '747a8c9b302e38de53fc89d9a5c487ef013a5de1db691676e5b438740b7d3968' 
  AND token = 'iqL62TX2KEaYNX9JOWcpHoBOjUsjfGGvtHdxdcZPFwc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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