SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3f51cb3755bbd14b9a6ce28f1c126a73991abe4738acca3e2cd9496831bd93a' 
  AND token = 'PzlpkGNCbWYJTr630T7mHvuowamXuFhVGT1vTIButfk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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