SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a97428a7d886a712349fc38a329545e203e2a798b2805b92f76a99c416184b3' 
  AND token = 'X9JsQbDVqlbBk/1uAL8CXhyKKGpBruLSuB/yrbrz5Kw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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