SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f51c5b358c01da5c3fe7fac258adf88f9c1c060a51621b14ff92ad0a474761bc' 
  AND token = 'eCjdCg7IpcZciq0Qw4OvfXAvWH+4scfaPS9lQPfeXoI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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