SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb2358b168e8373630e29875c8dd8df04d3e59c0b56e643763f9ee2afad2ed17' 
  AND token = 'GiFVIqaJlar7kRfSitztON7EdfvM95SwFGvXatKFexo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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