SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cde46ab85dc56624b0b5a4d71c3310a313b79bbae527e12d145e9052de65ca58' 
  AND token = 'W+gUCOnvHt+ohL/2Yvq+8Vde5y2ohN4Rqyaj+OEcNKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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