SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2844cb44045433b89576c52badedf4d4afe5bec509c88eb4573f464b11b34ec' 
  AND token = 'p2v4H+lWRPgYajAkHSJvFHuwUCUUffmDo2H2TR20PsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}