SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '645aca4335a362c47fba198d1b27ea471f19fd23161d6ff7eed0f9ddaa1c8de6' 
  AND token = 'Ht+i1+g2dMHOg1ydcRZc5iDD+z2Zma5+lcRXxRBb9UI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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