SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e407271aff39024a4eec818bad257814192ed18372de3b9dc9e416afa45fc5c' 
  AND token = 'qj1sf0HDkNxN/xtAyABcgE3boPBcVrCYxEazFlcZaAg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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