SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3042e0e0254c4b0ad97c514f30e8347bb7288fd529152bfdd8ee21537fb4ba5' 
  AND token = 'XY/L6GcxY4dSGJyjsOFKwjKjp3HE1hv3Q2WuUiwRgTQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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