SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03ef0bd70a96775fba96dc751e866e1014c86d8515a60c635f4fe342b7c878b8' 
  AND token = 'RdEp3WHiVcyvlutvch7r94guo5dOXyTZMAC4E920aWE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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