SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8db36e692bbe4044674744df3e39b94e23a60384490ca8f16df29698376267c4' 
  AND token = 'G68K/IGuD1xFNUd6bHDq3j1px4Ds3HDNxXSPcFQAVvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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