SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38eaae21c03fe7e5ab44c17f1a6b0bf705f5b301394c2da5e7ff9a9b998fbef8' 
  AND token = 'zK+KLFVBYPa25tFu6J/AGkajR5ILQ+cCldMU19ajzuI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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