SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e2c318b1771b576ceccba23f91b618a95b7f660272e9bca03fda74a8ac785e6' 
  AND token = 'jOrC8V+Aq2mJ74BQmMN44aNwnKOsKintUk8EiPDqeqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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