SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0779763692a92f1d033c81678873e691a0c3ffee9794196cfbef2fc2b200bef0' 
  AND token = 'bMRekyfVEiSVotLDers3cLZSoEMC+Sihw3bOAgTdnSE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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