SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3faf0f2f5903895ce7d3ef761a17744aae870e504e84e7d7f04061292e6744aa' 
  AND token = 'mT6lhMLwE+W+ddJNBzdKVmeh95tEz1h6+FpardquQMo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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