SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '645876053ca097826b05755252f1e4ab49bca76af6289c12458eea816c0d5f45' 
  AND token = 'Nyp2/VzEMiGErINJzHHm6nb40qKpTQRZNbHt/uFYR8Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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