SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ccc6c312bf17acced4e1d765680d0d2fa13662e336dc1d46baed84a334d7e229' 
  AND token = '+xei8kajcPaDA7OSf4ctm8nlqWnglQPmckzID0NLkqE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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