SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '518ba7c3f54be4fd41633c2f6be4f14bf1c175dbfa0feb7cbf865af4a363e76e' 
  AND token = 'Aeo+u+yfgBtkD/w4G+U49SDbY5rvmEnuGEwJc/N/Isc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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