SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '963d8e6b745c6634cc151891e2d09fab4d73be6fb85d7eab977b7942d7274da7' 
  AND token = '29uMCTmlYTaH8trPhcREegtHsrFYVY6KhCEhD9plco8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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