SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7186f51a402318f753b3bbbbaeca82dd89321e92af5af31630532a85ccda1af7' 
  AND token = 'OvbVZWJdhjXHF6cw0z+PzEWet3ibNlPdH6+AhvF5KTM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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