SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c305638b1afbb48b53a8511e753357a81658fad4fa1ff505ee9e778c30db28fd' 
  AND token = 'jWwaYNDwAx8M/BRSDuzbQF8bsql8EaNASrjF7QQAuKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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