SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b92dff74fa25ce0b22723f53512d05e9d971dc78fc4441afc49f858843136b40' 
  AND token = 'PNN5cEqyszIzyz6VPtT4m5yAs4HQkw8DZw5fp1D7kR8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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