SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fc5bb2630373d3896dad90604fb837e743c0a5e25a2a18f75dd4d87faba68c9' 
  AND token = 'tCP9Q1BxZcCwozXoA6LTfFIBZKVNtdpD2X9FjF+SnDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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