SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92cd12f373f9435a5bfbb4704d8afd0c1881937ddbb331c2c1fc99ab90c1b734' 
  AND token = '6gp07KcixYr9hOtOhtGtDaQhbbEal2dRdSVEETSteJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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