SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73ae4d2e5139342a532fea58e8be053564148ecbe8c7122b917f1efe4003f608' 
  AND token = 'jvEOCg882uc6dYN8FVSSCzFkuZwiHIMob/Mv0eCr3yM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}