SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3789dc7214f53d88751a0a62e3474e0c712cf93051c22cfdd643d57a20d0b34e' 
  AND token = 'jKgGq+y/3P7wrrlxsJQzAghYTbduRrWqMHOwcrMdYPU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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